A crawler is also called as a spider in search engine terms. Spider always looking for indexing a page in web links(Site map).
Google is most popular search engine in the digital world when compared with yahoo and bing. Google uses Search algorithms to rank a website. Google bot is the crawler which crawls the site with sitemap links and robots.txt file guidance.
Google Penguin, Google Panda, Google Humming bird are major search algorithms which ranks the website, if sites have good content and it also penalize the site if sites have low content and build with black hat SEO method.
Google always recommends white hat SEO method for search engine optimization. White hat SEO takes long time to rank well in google. it takes minimum six months to rank a single page on google search page rank. On-Page optimization and Off Page Optimization is the success key for White hat SEO method.
Fetch with Google Crawler
Google delivers the correct and relevant search results to the right people based on user search queries. Search results can varied from one location to other location based on country localization with local domain systems.
Example: esearchadvisors.com is the famous digital marketing services in India. If any Indian user search for digital marketing services means Google shows esearchadvisors.com as first results in India. In other country like united states, Google shows moz.com as digital marketing services.
Note: Try to avoid black-hat seo methods like keyword stuffing,buying links from other sites,hiding text with css,showing irrelevant content with meta description and over optimization.
Tips to rank quickly on Google:
Use Google Webmaster Guidelines For optimization and search indexing purposes. Use responsive template theme for websites on mobile devices and tablets. Use best CMS (Content Management Software) like WordPress,Joomla,Drupal,Bloggger, for website creation.